icon($str, $width, $height)
  background url($str + '@2x.png')
  background-size $width $height
  display inline-block
  width $width
  height $height
  vertical-align top
  @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3)
    background-image: url($str + "@3x.png")

ellipsis()
  text-overflow: ellipsis
  overflow: hidden
  white-space: nowrap

no-wrap()
  text-overflow: ellipsis
  overflow: hidden
  white-space: nowrap

center($pos)
  position $pos
  top 50%
  left 50%
  transform translate(-50%, -50%)

wrapper($pos, $z)
    position $pos
    left 0
    top 0
    width 100%
    height 100%
    z-index $z